Universal mobile keyboard

ABSTRACT

A versatile and mobile keyboard and a highly energy efficient keyboard scanning method are provided. The keyboard may be used with a variety of mobile devices such as PDAs, cellular phones, and tablet PCs, through various interfaces such as an IR, USB, or Bluetooth™ interface. In particular, an IR head assembly is provided that includes an IR head, a movable arm on which the IR head is mounted, and a connector for attaching to a docking structure. The docking structure may be attached to a keypad, which is electrically coupled to the IR head for transmitting keystroke data through the IR head. When a mobile device is docked on the docking structure, the arm in the IR assembly may be moved to an optimal distance from the IR port of the mobile device to ensure high communication performance between the keyboard and the mobile device. An energy efficient keyboard scanning method utilizes higher-valued pull-up resistors for energy conservation. The keyboard scanning method includes a charging step to charge stray capacitance associated with the keys. The keyboard scanning method can also be operated at a variable scanning frequency.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention generally relates to keyboards for mobile devices.More particularly, the present invention relates to a universal mobilekeyboard including an infrared interface and an energy-efficientkeyboard scanning method.

2. Discussion of the Related Art

Personal digital assistants (PDAs) have become more popular andaffordable with improved technology, allowing for enhanced displayquality, color richness, contrast, processing speed, power efficiency,memory capacity, RF communication capability, and other desirablecharacteristics. Similar advances are also made in other mobile devices,such as cellular phones, smart phones (PDA plus cellular handset),industrial data terminals, and tablet PCs. Thus, there is a growing needfor an efficient and convenient universal device and method for dataentry and for providing a user interface with these mobile devices.

Some mobile devices offer touch-sensitive LCD screens with built-inrecognition software for data input by handwriting or “graffiti.”However, data input using graffiti is not convenient or efficient unlessthe user is properly trained in the method. Even then, data input usinggraffiti is not usually as fast as using a keyboard.

Some PDAs have built-in soft or virtual keyboards, or other input means,such as thumb-boards, silk-screen keyboards, and rubber keyboards.However, these input means are less efficient than small foldablekeyboards that connect to the mobile device, such as a PDA, and offerthe familiar desktop/notebook keyboard input style.

Such small foldable keyboards typically require a connector customizedfor each mobile device make or model. Usually a device-specificconnector is used for both data exchange and for holding the mobiledevice in place. Such a connector often lacks stability. Also, when auser gets a new mobile device, the user would also need to purchase anew keyboard. Some keyboards provide changeable connector heads.However, these changeable connector heads achieve only limitedflexibility, given the many connector types that are used among mobiledevices.

Accordingly, wireless keyboards (e.g., infrared-based keyboards) aredesired. However, typical infrared (IR)-based keyboards in the prior artsuffer from several disadvantages. For example, a typical prior art IRkeyboard uses a polished metal reflector to guide the IR beam from thekeyboard to the IR port of a mobile device, which can be found at thetop or at the side of the mobile device. Such a polished metal reflectoris awkward to adjust and difficult to keep steady. Furthermore, toachieve the IR beam reflection, a stronger IR beam intensity thanotherwise needed for data transmission is used. Thus, battery energy isinefficiently used, resulting in a shorter battery life or requiring alarger number of batteries (e.g., from 1 to 3 AAA batteries) or a higherbattery capacity. In addition, a stronger than required IR beamintensity may also in some instances overwhelm or “blind” the IRreceiver circuitry in a mobile device IR port, causing data error or asluggish response. A reflector-based IR beam guidance scheme has limitedflexibility in aligning to IR ports, as the IR port may be found in anyof a variety of possible locations on a mobile device.

Therefore, what is needed is a keyboard for a mobile device that isoperable with a large number of mobile devices. In particular, akeyboard with an IR interface is needed that is operable with andadjustable for a variety of possible IR port locations found on variousmobile devices. Additionally, a keyboard scanning method is needed thatis highly energy efficient to increase battery life and improve keyboardportability.

SUMMARY

The present invention provides a universal keyboard that includesmultiple interfaces for operability with a variety of mobile devices,such as PDAs, smart telephones, and cellular telephones. Furthermore, ahighly energy-efficient method for scanning a keyboard is provided.

According to one embodiment of the present invention, a universalkeyboard includes an IR head capable of transmitting data, an armoperably coupled to the IR head, a docking structure, a connectoroperably coupled to a base of the arm and the docking structure to allowthe arm movement within a plane, and a keyboard device operably coupledto the docking structure and the IR head, such that data entered on thekeyboard can be transmitted by the IR head to a mobile device placed onthe docket structure.

According to another embodiment of the present invention, a universalkeyboard selectably operates an IR interface, a USB interface, or aBluetooth™ interface to transmit data input on the keyboard over theselected IR interface, the USB interface, or the Bluetooth™ interface.

According to another embodiment of the present invention, a method for alow-power operation of a keyboard provides a micro-controller havingoutput pins and input pins, wherein each key of the universal keyboardis coupled to both a designated output pin and a designated input pin,providing each input pin a pull-up resistor operably coupled to avoltage source. The pull-up resistor has a value between about 1mega-ohm and about 100 mega-ohms to decrease power consumption. Tooperate this universal keyboard, a selected output pin is placed at afirst voltage level, for example ground voltage level, and each inputpin is then sensed to determine if a selected one of the keys associatedwith the selected output pin and one of the input pins is depressed. Ifthe key is depressed, the output pin corresponding to the selected keyis driven to a second voltage level, for example power source voltagelevel, to recharge the stray capacitance associated with the output pinand the selected input pin. After recharging, the output pin is put inhigh-impedance state and depends on the pull-up resister to maintain thevoltage level.

The present invention allows for great flexibility in transmitting datato an IR port located at any of many positions on a mobile device whilealso providing a highly energy efficient keyboard scanning method.

According to another aspect of the present invention, a method isprovided whereby the software driver for operating the keyboard isdownloaded from a storage medium in the keyboard to a mobile device,according to the make and model of the program device, without having toplace the mobile device in a cradle or a docking device attached to adesktop computer or a notebook computer.

These and other features and advantages of the present invention will bemore readily apparent from the detailed description of the embodimentsset forth below taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A–1D show different views of an unfolded universal keyboard inaccordance with an embodiment of the present invention.

FIGS. 2A–2D show different views of an unfolded universal keyboard withan example of a docked PDA in accordance with an embodiment of thepresent invention.

FIG. 3 shows an unfolded universal keyboard with an example of a dockedcellular telephone in accordance with an embodiment of the presentinvention.

FIG. 4 shows an unfolded universal keyboard operably coupled to anexample of a docked tablet PC in accordance with an embodiment of thepresent invention.

FIGS. 5A–5B show an unfolded universal keyboard in accordance withanother embodiment of the present invention.

FIGS. 6A–6B show the outer surface of the folded universal keyboard ofFIGS. 5A–5B in accordance with an embodiment of the present invention.

FIG. 6C shows a docking structure, IR head, arm structure, and connectorof the universal keyboard of FIGS. 5A–5B in accordance with anembodiment of the present invention.

FIGS. 7A–7C show different views of the outer surface of a foldeduniversal keyboard, IR head, arm, and connector in accordance withanother embodiment of the present invention.

FIG. 8 shows an example of a foldable keyboard with a locking mechanismin accordance with an embodiment of the present invention.

FIGS. 9A–9C show a central hinge of a universal keyboard in accordancewith an embodiment of the present invention.

FIGS. 10A–10B show a central hinge of a universal keyboard in accordancewith another embodiment of the present invention.

FIG. 11 shows an example a mouse or cursor selector in accordance withan embodiment of the present invention.

FIGS. 12A–12B show different views of a folded universal keyboard with atop cover in accordance with an embodiment of the present invention.

FIG. 13 shows an example of an inside surface of a top cover that iscapable of holding various cards and memory devices.

FIG. 14 shows an example of an IR, USB, or Bluetooth™ interface selectorin accordance with an embodiment of the present invention.

FIG. 15 shows an example of a universal keyboard circuit diagram inaccordance with an embodiment of the present invention.

FIG. 16 shows an adaptor for a USB interface, according to oneembodiment of the present invention.

FIG. 17 shows an adaptor for a Bluetooth™ interface, according to oneembodiment of the present invention.

FIG. 18 shows Circuit 1800 suitable for implementing switching betweenbattery power (IR interface) and a serial or USB interface.

Use of the same reference symbols in different figures indicates similaror identical items. It is further noted that the drawings may not bedrawn to scale.

DETAILED DESCRIPTION

The present invention provides a universal keyboard that can be usedwith any of a variety of mobile devices, such as PDAs, cellular/smartphones, and tablet PCs. The present invention also provides a universaland highly energy efficient keyboard.

FIGS. 1A–1D illustrate an unfolded universal keyboard 100, in accordancewith one embodiment of the present invention. As shown in FIGS. 1A–1D,an infra-red (IR) head assembly 101 is mounted on a docking structure108, which is attached to keypad 116. Top cover 112 may also optionallybe included with universal keyboard 100.

In one embodiment, IR head assembly 101 includes IR head 102, which ismounted on an arm 104 that is rotatable about an axis perpendicular to aplane of docking structure 108, and connector 106. IR head 102 includesan IR light emitting diode (LED). In one embodiment, the LED is biasedto conduct an electrical current that provides an IR beam intensitycalculated to achieve a high IR signal-to-noise ratio and a small IRdata error rate, based upon an estimation of the minimum and maximumdistances between IR head 102 and an IR port of a mobile device that canbe mounted on the docking structure 108. In one implementation, theminimum and maximum IR beam distances are determined to be about 0.3 cmand about 3 cm, respectively. In that implementation, using acommercially available IR LED Vishay TSMF1000, the electrical currentsupplied to the IR LED may range between about 2 mA to about 10 mA.

IR head 102 may be mounted on arm 104 by a hinge 103 or other suitablemechanism in order to enable IR head 102 to be positioned at any of arange of angles relative to arm 104 (FIGS. 1C and 1D). Arm 104 ismounted on docking structure 108 by connector 106 (e.g., a ball bearing)that allows arm 104 to rotate around an axis perpendicular to a plane ofdocking structure 108. The location of connector 106 and the length ofarm 104 are selected to allow IR head 102 to be positioned forline-of-sight communication with an IR port of any of a large number ofmobile devices that can be mounted on docking structure 108, regardlessof their IR port locations. To ensure a consistent electrical current toIR head 102 regardless of the position of rotatable arm 104 and tomaintain a relatively thin structure, a circular multi-hub coppercontact structure is included in connector 106. In one example, arm 104has a length of about 8 cm. In addition, in one implementation, one ormore batteries that are housed in arm 104 power IR head 102.

In one embodiment, docking structure 108 includes spring-loaded movabledevice holders 110 for securely holding in place a mobile device (e.g.,a PDA, a smart phone, or a tablet PC) oriented in one of many possibleorientations, such as shown in FIGS. 2A–2D, 3, and 4. FIGS. 2A–2B show aPDA 202 securely docked in a “portrait” position on docking structure108 and FIGS. 2C–2D show a PDA 202 securely docked in a “landscape”position on docking structure 108. FIG. 3 shows a cellular phone 302securely docked on docking structure 108 and FIG. 4 shows a tablet PC402 securely docked on docking structure 108.

As noted above, a prior art connector-based keyboard uses the connectorto hold the mobile device in place, often resulting in an unstableconfiguration. By contrast, holders 110 are designed and positioned tosecure onto docking structure 108 any of a large number of mobiledevices of various lengths, widths, and thicknesses. Grooves into whichholders 110 may be folded or retracted are provided on one surface ofdocking structure 108 (FIG. 1B). Holders 110 are designed to be flushwith the surface of docking structure 108, when folded or retracted intothe grooves. Holders 110 need to be placed and/or shaped only as shownin FIGS. 1A–1D. Holders 110 may be placed in various positions andformed into various shapes with corresponding grooves to securely hold amobile device. FIGS. 5A–5B illustrate examples of other spring-loadedholders 510 that may be used in accordance with the present invention.

In one embodiment as further shown in FIGS. 1A–1D, docking structure 108includes a recessed area 111 on an inside surface of docking structure108 at which connector 106 connects to IR head assembly 101. Recessedarea 111 allows the arm structure of IR head assembly 101 to freely movethrough a large range of angles when a mobile device is docked, andprovides the universal keyboard a thin profile when docking structure108 is in the folded position for storage.

Alternatively, IR head assembly 101 may be mounted on an outer surfaceof docking structure 108 to enable more holders or holder structures tobe provided on the inside surface of docking structure 108, such that agreater number of mobile devices of various shapes and sizes can be heldby docking structure 108 in a variety of positions (e.g., in portrait orlandscape positions).

FIGS. 5A and 6A–6B show an IR head assembly 501 that is provided on anouter surface of docking structure 508, with a recessed area into whichIR head assembly 501 can be secured when the IR keyboard 500 is in thefolded, or storage position. In that configuration, the properly securedIR head assembly 501 is substantially flush with the outer surface ofdocking structure 508.

FIGS. 7A–7C show IR keyboard 700, according to another embodiment of thepresent invention, in which IR head assembly 701 is mounted by aspring-loaded mechanism to an outer surface of docking structure 708. IRhead assembly 701 may be placed within a recessed area of the outersurface of docking structure 708 in the storage or folded position (FIG.7A). IR head assembly 701 can be lifted up from the recessed area (FIG.7B), and be allowed to move freely along a circular arc that is parallelto the surface of docking structure 708 (FIG. 7C) and centered about anaxis perpendicular to docking structure 708.

Referring back to FIG. 1C, docking structure 108 may also include stand120 which is attached to the outer surface of docking structure 108.Stand 120 may be slotted into any one of several grooves 122 provided onthe inner surface of top cover 112, such that docking structure 108 canbe supported at various inclined angles relative to the surface of topcover 112. Alternatively, stand 120 may be made free-standing at one ofvarious inclined angles on the flat surface on which IR keyboard 100 isunfolded. FIG. 6C shows IR keyboard 500 having stand 510 supporting anouter surface of docking structure 508 at various inclined anglesrelative to the surface on which keyboard 100 is placed. Alternatively,referring back to FIG. 1C, stand 120 may be attached to top cover 112and may be coupled into any one of several grooves formed into an outersurface of docking structure 108.

Docking structure 108 may also include battery compartment 109 to holdone or more batteries used for providing power to IR head 102. Ofcourse, battery compartment 109 need not be placed in docking structure108 but may also be placed in keypad 116 instead. FIG. 5B showsbatteries 530 being placed in battery compartment 109 provided at theupper left hand corner of keypad 116.

As shown in FIGS. 1A–1D, in one embodiment, keypad 116 includes foldablesections 116 a and 116 b joined by a central hinge or coupler 118.Alternatively, as shown in FIG. 8, keypad 116 includes latch 802 that,when moved to an “open” position, locks keypad sections 116 a and 116 bin a spread-flat position to allow a steady surface to facilitate touchtyping.

FIGS. 9A–9C and 10A–10B illustrate two central hinge mechanisms that canbe used to couple two keypad sections and allow them to fold and unfoldproperly, in accordance with two embodiments of the present invention.According to one embodiment, shown in FIGS. 9A–9C, keypad section 902 aand 902 b each include plates 904 provided on opposite sides of thekeypad section and connected by rod 908, thus forming a hinge aboutwhich plates 904 can rotate. Plates 904 of keypad sections 902 a and 902b on each side of the keypad sections are connected by central faceplate 906. Plates 904 are each provided teeth-like structures. Centralface plate 906 keeps keypad sections 902 a and 902 b properly aligned byensuring the teeth on plates 904 on keypad sections 902 a and 902 bproperly mesh during folding or unfolding keypad 902. Central face plate906 is kept centered at all times during folding or unfolding (i.e.,does not slide to either side of center line A), thus allowing forprecisely positioned opening and closing of keypad sections 902 a and902 b. FIG. 9A shows a side view of a completely folded keyboard device.Keypad sections 902 a and 902 b are aligned such that plates 904 areproperly meshed when folding or unfolding the keypad sections, as shownin FIG. 9B. FIG. 9C shows a completely unfolded keyboard device.

FIGS. 10A–10B illustrate another hinge mechanism that may be used inaccordance with another embodiment of the present invention. FIG. 10Ashows a top view of keypad sections 1002 a and 1002 b coupled by a hingemechanism. Keypad sections 1002 a and 1002 b each include a pair ofarms, designated 1004 a for keypad section 1002 a and designated 1004 bfor keypad section 1002 b. For each keypad section, the arms are locatedon opposite side of the keypad section. Between the arms in each pair ofarms (i.e., each of arms 1004 a and 1004 b) is provided a cylindricalthrough-hole for receiving a pin (designated pin 1006, as shown bydashed lines in FIG. 10A) that runs the length of the through-hole. Whenthe keyboard is unfolded, keypad sections 1002 a and 1002 b each rotatearound the pins 1006, while coupler 1008, shown by a side view in FIG.10B, couples pins 1006 to keep the keypad sections 1002 a and 1002 bproperly aligned during folding and unfolding. Of course, various othervariations of hinge mechanisms, such as a single rod with meshed arms,may also be used within the scope of the present invention.

According to another embodiment of the present invention, FIG. 11illustrates keypad 1116 on which are provided mouse and cursor controls1102. A toggle switch or button is provided to activate alternativelykeypad 1116 for cursor and mouse functions.

In one embodiment, the keyboard driver software, including softwaredrivers needed for controlling the mouse or cursor functions are loadedinto a mobile device from a compact disk through a desktop or notebookcomputer. Alternatively, the keyboard driver software can be preloadedby the manufacturer of a mobile device. According to one embodiment ofthe present invention, the driver software can be provided in one ormore removal storage devices (e.g., a flash memory card) that can beplugged into a card reader installed on the universal keyboard. In thatembodiment, when the universal keyboard first communicates with a mobiledevice over a wireless, USB or another serial interface, the universalkeyboard queries the make and model of the mobile device and downloadsfrom the removable storage device into the mobile device the appropriatesoftware drivers to control the universal keyboard, including the mouseand cursor functions. Using this arrangement, it is not necessary todownload the keyboard software from a desktop or notebook computer tothe mobile device, using a docking station or cradle of the mobiledevice.

As further shown in FIGS. 1A–1D, top cover 112 may be included withuniversal keyboard 100 to provide a protective top surface and coveringto the folded keyboard. In one embodiment, as shown in FIGS. 12A–12B,top cover 1212 folds over docking structure 1208, folded keypad 1216,and central hinge 1218. As discussed above, the IR head assembly can bemounted to either the inner surface or outer surface of the dockingstructure, and the top cover may be designed to accommodate eitherconfiguration.

FIG. 13 illustrates inner surface 1300 of top cover 1212, withaccommodation of various accessories, according to one embodiment of thepresent invention. As described above, inner surface of top cover 1212may include grooves 1322 for holding a stand in place. Furthermore, theinner surface of top cover 1212 may include recesses for accessories,such as memory cards, compact flash (CF) cards, secure digital (SD)cards, multi-media cards (MMC), memory sticks, and PCMCIA (PC) cards.

As shown in FIGS. 1A–1C, curved arrows A–C indicate the manner in whichuniversal keyboard 100 is folded and unfolded, in accordance with anembodiment of the present invention. To fold universal keyboard 100,section 116 a first folds over section 116 b, as illustrated by arrow Ain FIG. 1A. Then, docking structure 108 and top cover 112 may fold overfolded key pad section 116 a, as shown by arrows B and C. In order toopen or unfold universal keyboard 100, docking structure 108 is firstunfolded in the manner indicated by arrow A in FIG. 1B. Then, keypad 116a is unfolded away from keypad section 116 a in the manner indicated byarrow B in FIG. 1B. Docking structure 108 may then be pulled away fromtop cover 112 and set at an inclined angle, as shown by arrow C in FIG.1C. In other embodiments, docking structure 108 and top cover 112 may becoupled so that docking structure 108 and top cover 112 open and closetogether, automatically moving with one motion by the user.

According to another embodiment of the present invention, the universalkeyboard includes not only an IR interface but a universal serial bus(USB) interface and a Bluetooth™ interface. As shown in FIG. 14, auniversal keyboard may include interface switch 1402 that controls whichinterface is active. Interface switch 1402 may be set by a user, or by asensor sensing whether the universal keyboard is coupled to communicateover the USB or Bluetooth™ interface. Driver software for each mobiledevice type, brand, and model are loaded into the corresponding mobiledevice to allow the mobile device to communicate with the universalkeyboard.

A USB interface applies well to any tablet PC (FIG. 4) or other productsequipped with a host-USB port. In one embodiment, the universal keyboardof the present invention has a built-in USB port for connecting anintelligent USB cable to host-USB equipped products.

Alternatively, the universal keyboard may provide simply 4-pin connectorinto which a USB adaptor, a Bluetooth™ adaptor, or another adaptor toanother industry standard interface may be provided. FIGS. 16 and 17show respectively an adaptor for a USB interface and an adaptor for aBluetooth™ interface. As shown in FIG. 16, adaptor 1600 includes serialport connector 1601 for coupling into a corresponding serial port onuniversal keyboard 100. Serial port 1601 includes power pin 1601 a,input pin 1601 b, output pin 1601 c and ground pin 1601 d. In USBadaptor 1600, the power and ground signals are provided as correspondingpower and ground signals in USB connector 1602. USB adaptor chip 1603(e.g., microcontroller integrated circuit MC68HC908JB8) can beprogrammed to translate between the signals in input pin 1601 b andoutput pin 1601 c and the corresponding signals in a USB Human InterfaceDevice (HID). Similarly, as shown in FIG. 17, Bluetooth™ adaptorintegrated circuit (e.g., the BlueCore™ integrated circuit from CSRLimited, Cambridge UK) 1702 translates between the signals in input pin1601 b and output pin 1601 c and corresponding signals under theBluetooth™ standard. In FIG. 17, power is provided by a battery inadaptor 1700, and signals over the Bluetooth™ interface is transmittedand received through antenna 1703.

Unlike PDAs or smart or cellular phones, no driver software is requiredto operate a tablet PC using a USB interface. Once a cable (e.g., a USBcable) is inserted into the universal keyboard's port (e.g., serial port1601 described above), a circuitry in the universal keyboard of thepresent invention automatically senses the inserted cable and turns offelectrical current to the IR head, and switches to a serial mode or aUSB mode, depending on whether the inserted cable is a serial cable or aUSB cable. Under the serial mode or the USB mode, the universal keyboardtakes power from the host system (e.g., tablet PC). FIG. 18 showscircuit 1800 suitable for implementing switching between battery power(IR interface) and a serial or USB interface. As shown in FIG. 18, asensor sensing whether or not a cable is inserted into serial port 1601controls switch 1802 between a “door open” (i.e., cable inserted, serialor USB port mode) and a “door closed” (i.e., no cable inserted, IRinterface mode). When switch 1802 is in a “door open” position, power tomicrocontroller 1804 (i.e., the controller for universal keyboard 100)is provided by power pin 1601 d from the external device. When switch1802 is in the “door closed” position, power to microcontroller 1804 isprovided by internal battery 1803.

Alternatively, in one embodiment, to select the IR interface, the userplaces a switch in the “IR” position. In that position, the switchphysically obstructs the USB port. Alternatively, when the switch isplaced in the “USB” or “serial” port position, the USB serial port isactivated. Such an interface switch prevents the IR port and the USB orserial port to be simultaneously activated. Prevention of simultaneousactivation of the IR and USB ports is desirable because, when the IRport is selected, the battery in the keyboard is in the activedischarging mode. At the same time, if the USB or serial port is alsoactive, the power from the USB host system force-charges the keyboardbattery, and hence causing a possible hazard.

The Bluetooth™ interface can be provided in any PDA, smart or cellularphone, tablet PC, or other mobile product equipped with Bluetooth™capability, either embedded or externally attached through an adapter ormemory card, in one example. When a Bluetooth™ module is plugged intothe USB port of the universal keyboard, the keyboard circuitryautomatically senses the Bluetooth™ module and turns off electricalcurrent to the IR head and switches to the Bluetooth™ module, accordingwith one embodiment of the present invention.

In accordance with another embodiment of the present invention, a methodfor low-power scanning a keyboard is provided utilizing an example of akeyboard circuit shown in FIG. 15. In one embodiment, micro-controller1506 controls keypad 1516 of universal keyboard 1500 using input pins1508 (usually 8) to micro-controller 1506 and output pins 1510 (usually10 to 19) from micro-controller 1506. Output pin 1512 frommicro-controller 1506 is also connected to an infrared light emittingdiode (IR LED) 1514, which transmits data to a mobile device through IRradiation. According to the present invention, an appropriate low-powermicro-controller (e.g., a 3-volt micro-controller) is chosen to controluniversal keyboard 1500.

Keypad 1516 of universal keyboard 1500 includes keys 1504, each of whichis electrically connected to one of input pins 1508 and one of outputpins 1510. Thus, when a user depresses a key, one of the input pins isshorted to one of the output pins. For example, when a user depresseskey 1504 a, input pin 1508 a and output pin 1510 a are shorted. Thisshort circuit can be sensed by applying a known voltage briefly andsuccessively on the output pins one at a time, and then sensing thevoltage at each of the input pin successively while the voltage is beingapplied to the output pin. This process for detecting the depressed keyis termed “keyboard scanning.” In the embodiment shown in FIG. 15, eachof input pins 1508 is connected to a power supply 1518 throughindividual pull-up resistors 1502. Thus, in the absence of an appliedvoltage on the output pins, input pins 1508 are pulled up to the powersupply voltage level, or “high” level. In the prior art, such pull-upresistors are usually in the tens of kilo-ohms range, so that a fewtenths milliampere of current flow through the pull-up resistor when aconnected output pin is driven to a “low” level. In the prior art, thepull-up resistor value cannot be increased because stray capacitances inthe wires that connect to the keys are of the order of hundreds ofpicofarads. A higher resistor value would result in an unacceptablylarge RC time constant. The RC time constant limits how quickly an inputpin can return to the high level ready for detecting the next depressedkey.

According to the present invention, the firmware of micro-controller1506 “scans” the keyboard device of universal keyboard 1500 by firstdriving one of the output pins 1510 to the ground or “low” level, whileleaving all other output pins 1510 in a high impedance state. When ashort circuit is created due to a depressed key, the input pincorresponding to the depressed key is pulled to a low level by a lowvoltage on the output pin corresponding to that depressed key.

The firmware of prior art keyboards scan the keyboard at fixed timeintervals (e.g., once every 10 to 40 milliseconds). Because of the lowresistance in the pull-up resistors, each scan consumes a considerableamount of energy. The longer the scanning interval (i.e., the lessfrequent the keyboard is scanned), the less energy is used on theaverage. However, the scanning interval must be short enough to maintainresponsiveness to the user's typing. Otherwise, the scanning mechanismmay miss some of the keys depressed by a fast typist.

According to one embodiment of the present invention, rather than usinga fixed scanning interval, an adaptive scanning interval is used. Thescanning interval according to the present invention is determined bythe frequency in which keys 1504 are depressed and released. When keys1504 are depressed and released quickly, the firmware shortens itsscanning interval so that it does not miss any user action. When thefirmware senses that keys 1504 are depressed and released lessfrequently, it lengthens the scanning interval to conserve energy.

In accordance with another embodiment of the present invention, thevalue of pull-up resistors 1502 is increased above 100 kilo-ohms,preferably in the multiple mega-ohms range (e.g., 1 to 100 mega-ohms),thereby reducing the current consumption during scanning from tenths ofmilliamperes to microamperes. A slow recovery time is avoided by aspecial step in the scanning process. Each time a depressed key isdetected, and before the corresponding output pin is put back into ahigh impedance state, the output pin is momentarily driven high torecharge the stray capacitance of the wire. The slow recharge throughthe large pull-up resistor is therefore avoided. Thus, even though amuch larger pull-up resistor value than that in the prior art is used,the universal keyboard of the present invention does not result in akeyboard with slower responsiveness.

Accordingly, the low-power keyboard scanning method in accordance withthe present invention is more energy efficient than prior art keyboards.The low-power keyboard scanning method of the present invention allowskeyboards of the present invention to use two low-cost CR2032 coinbatteries for up to six months under a typical usage of two hours ofcontinuous typing per day. Prior art keyboards required batteries thatare capable of a higher electrical current and a higher energy capacity.

The above-described embodiments of the present invention are merelymeant to be illustrative and not limiting. Various changes andmodifications may be made within the scope of this invention. Therefore,the appended claims encompass all such changes and modifications.

1. A universal keyboard, comprising: a docking structure foraccommodating a mobile device; an arm having a first end mounted on thedocking structure at one end by a connector, and having a second freelymovable end, such that the second freely movable end of the arm tracesan arc centered about the connector over a predetermined range ofangles; an infrared (IR) head mounted on the freely movable end of thearm for receiving and transmitting data over a wireless link; a keypadthat is physically coupled to the docking structure, and providingelectrical signals representing the keys on the keypad that aredepressed by an external agent; and a controller circuit receiving theelectrical signals and converting the electrical signals into data fortransmission by the IR head over the wireless link.
 2. The universalkeyboard of claim 1, wherein the IR head includes an IR light emittingdiode (LED).
 3. The universal keyboard of claim 1, wherein the IR headis powered by a battery.
 4. The universal keyboard of claim 3, whereinthe battery is a coin battery.
 5. The universal keyboard of claim 1,wherein the connector engages the arm to allow the arm to rotate aboutan axis perpendicular to the docking structure.
 6. The universalkeyboard of claim 1, wherein the connector comprises a ball and socketdevice.
 7. The universal keyboard of claim 1, wherein the connectorcomprises a rotatable member.
 8. The universal keyboard of claim 1,wherein the connector comprises a hinge mechanism.
 9. The universalkeyboard of claim 5, wherein the connector includes a circular multi-hubcopper contact structure.
 10. The universal keyboard of claim 1, whereinthe connector is mounted on a surface of the docking structure on theoutside of the universal keyboard in a folded configuration.
 11. Theuniversal keyboard of claim 1, wherein the connector is mounted on asurface of the docking structure on the inside of the universal keyboardin a folded configuration.
 12. The universal keyboard of claim 1,further comprises movable holders mounted on the docking structure toaccommodate any of a plurality of mobile devices.
 13. The universalkeyboard of claim 12, wherein one or more of the holders are provided aspring-loaded mechanism for securing the mobile device.
 14. Theuniversal keyboard of claim 1, wherein the keypad comprises a pluralityof keypad sections, wherein two of the sections are held together by ahinge, allowing the sections held to fold and unfold cooperatively. 15.The universal keyboard of claim 11, wherein the hinge comprises plateshaving engaged gear-like teeth that mesh during the folding andunfolding of the keypad sections.
 16. The universal keyboard of claim15, wherein plates are coupled by a face plate.
 17. The universalkeyboard of claim 14, wherein the key pad further comprises a latch forlocking the two sections of the keypad into a predetermined position.18. The universal keyboard of claim 1, wherein the keypad furthercomprises controls for operating a mouse.
 19. The universal keyboard ofclaim 1, wherein the keypad further comprises controls for operating acursor.
 20. The universal keyboard of claim 1, further comprising acover that folds over the docking structure in a folded position of thekeyboard.
 21. The universal keyboard of claim 20, wherein recesses areprovided on the inside surface of the top cover to accommodate a removalstorage device.
 22. The universal keyboard of claim 1, furthercomprising a foldable stand for supporting the docking structure whenthe universal keyboard is in an unfolded position.
 23. The universalkeyboard of claim 22, further comprising grooves provided on a surfaceof the docking structure, each groove being provided for fixing thedocking structure in a predetermined position.
 24. The universalkeyboard of claim 22, further comprising a protective cover that foldsover the docking structure in a folded position of the keyboard, theprotective cover having a plurality of grooves provided on one surface,wherein, in an unfolded position of the keyboard, the grooves areexposed to accommodate the stand, so as to support the docketingstructure in any one of a plurality of predetermined positions.
 25. Theuniversal keyboard of claim 1, further comprises: a protective coverthat folds over the docking structure in a folded position of thekeyboard; and a connecting structure coupling the protective cover andthe docking structure, the connecting structure placing both theprotective cover and the docking structure into a predeterminedconfiguration simultaneously as the universal keyboard is unfolded.